Plug for removing paraffing accumulating in oil conduits



Patented July 22, 1952 PLUG FOR REMOVING PARAFFIN AOCUMU- LATING IN OIL CONDUITS Harrell L. Bilhartz, Howard E. Greenwell, and Lawrence E. Davis, Dallas, Tex., assignors to The Atlantic-Refining Company, Philadelphia, Pa., a corporation of Pennsylvania No Drawing. Application January 7, 1950, Serial No. 137,478

1 14 Claims.

This invention relates generall to the removal of paraffin from production tubing, surface flow lines, and other conduits through which oil passes, and particularly to slowly soluble or disintegrable plugs adapted to be passed therethrough for removing paraffin deposits from the walls thereof.

Heretofore, various methods and apparatus have been proposed and used for removing par-' aifin deposits from the production tubing of oil wells and also from flow lines located on or near the surface through which oil is conducted from one location to another. The most used methods of paraffin removal have been those in which paraffin is simply scraped or cut loose from the wall of the conduit by a tool passed through it. Although such methods havebeen used with satisfactory results, a considerable amount of time is expended in the insertion and removal of the device from the flow line. For example, in the removal of paraffin from the production tubing of a well, it is usually necessary to remove the parafiin cutter from the well after having inserted the same in the production tubing and having passed it the entire length thereof before oil production can be continued.

In order to avoid these difficulties, solvents have been introduced into production tubings and flow lines to dissolve and remove paraffin accumulations therein. However, due to the low solubility of paraflin in the available solvents, comparatively large amounts of these are required. Other systems of parafiin removal have relied upon liquefying the solid deposits by the application of heat in some manner, such, for example, as by electricity, steam, hot water, and the like. While these systems are often satisfactory, special equipment ordinarily must be provided for generatin and transmitting this heat energy into the production tubing or surface flow line.

Accordingly, one object of this invention is to provide improved means for removal of parafiin deposits from production tubing, surface flow lines and other conduits which will obviate the above mentioned difficulties.

Another object is to provide means for removing paraffin deposits from the interior of conduits by cutting or scraping parafiin from the walls thereof.

A further object of thisinvention is to provide slowly soluble or disintegrable plugs, adapted to be passed through production tubing, surface flow lines and other conduits through which oil flows. thereby to remove by cutting or scraping paraffin deposited on the walls thereof.

Other objects and features of the invention will be apparent from the description which follows.

In accordance with this invention, paraffin deposits maybe removed from production tubing, surface flow lines, and other conduits by passing therethrough a plug comprising a slowly soluble or disintegrable base material and a rosin amine or a salt of a rosin amine and an organic acid. The plug is formed so as to fit snugly in the conduit through which it is caused to be propelled by applying fluid pressure on one end thereof. In order for the plug to effectively remove paraflin, it is necessary for it to be sufficiently hard that the forward end provides a cutting surface that will scrape or cut the paraffin upon contact therewith, to maintain shape and remain hard at temperatures in excess of the highest temperature expected to be encountered in temporary storage places, that is, in excess of approximately F., to dissolve or disintegrate in the oil flowing through the conduit within a desired period of time, such as, for example, from one hour to a day or more after passing through the conduit and removing the paraffin from the interior thereof, and to be free from shattering or breaking under pressures required for propelling the plug through the production tubing or flow line. This is accomplished in accordance with the invention by varying the percentages of the above mentioned components of the plug, dependent upon the conditions in each particular case.

The base materials may be exemplified by high melting point waxes, such as microcrystalline hydrocarbon waxes derived from petroleumand having melting points between 150 F. and 200 F.; ceresin; montan wax; chloro-waxes; waxes from the Fischer-Tropsch process; waxes from crude oil tank bottoms; high melting synthetic Wax-like materials such as the anilides and amides of the higher fatty acids; ester gums;

' high melting petroleum resins derived from crude oil residues by solvent treatment and/or oxidation; petroleum asphalts having softening points (R. & B.) between 200 F. and 300 F. and having a maximum penetration at 77 F. of 10,'and preferably between 5 and waxy asphalts derived from petroleum residuum by propane treatment; oxidized residues from thermal or catalytic oil cracking units; and residues from coal tar, coal tar pitch, and vegetable pitches; or mixture of two or more of these materials.

The rosin amine, and preferably the salt thereof with an organic acid, comprises the other component of the plug.

The rosin amines used for the production of such salts may be prepared from dehydrogenated rosin, disproportionated rosin, or hydrogenated rosin by first reacting with ammonia to form the nitrile and then hydrogenating the nitrile to the amine. carried out by passing gaseous ammonia into the molten rosin material and vaporizing the water as fast as it is formed or by heatingthe rosin material and ammonia in the presence of a dehydration catalyst. The nitrile is preferably purified by alkali extraction or by distillation to remove unconverted acids prior to hydrogenation to the amine, since the acidic materials frequently destroy the activity of the hydrogenation catalyst. The hydrogenation'o'f the nitrile may be carried out in the presence or absence of a solvent and in the presence or absence of ammonia. The catalyst may be any of the well-known 'hydrogenation catalysts such as Raney nickel,

- Raney cobalt, activated: nickel, cobalt, palladium or platinum, "etc., and supports may be used if desired. The hydrogenation is usually carried out under a pressure of'about 200 to about 8,000 pounds per square inch at a temperature of about f C.'to about 200 C. r 1

The rosin amine salts which maybe used in accordance with this invention include the salts of organic acids such as the higher fatty acids, for example, lauric, stearic, and palmitic acids; naphthenic acids having a molecular weight preferably between 170 and 350; sulfonic acids derived by the treatment of petroleum fractions with sulfuric acid; or other sulfonating agents. Of these, the oil-soluble sulfonic acids obtained as a by-product in the manufacture of mineral white oils are preferred, and these acids usually have a molecular weight between 400 and 550 and acid numbers between 80 and 140 mg. KOH per gram; Sulfonic acids derived from higher alkyl benzenes, naphthalenes, and anthracenes may also be used, aswell as carboxylic acids suchas abietic acid, and acids from the oxidation of parafiin wax. Particularly suitable are the rosin amine salts, of stearic acid, palmitic acid, and naphthenic acid. The rosin amine salts may be' prepared simply by mixing the amine with an equivalent amount of organic acid andheating, or by dissolving the amine and acid in a suitable solvent, heating if necessary, and then removing the solvent. The plugs of the present invention may be formed by melting the base material, and the rosin amine salt, if necessary, mixing these components in the desired proportions, and shaping the molten or plastic mixture to the desired contour or diinensions by molding or' extrusion. The base material constitutes from 90% to of the mixture and the rosin amine salt from 10% to, 45% of the mixture, depending uponthe properties desired in the finished plug.

.The following examples are illustrative of plugs which have been found to satisfactorily remove paraflin deposits under the various conditions indicated.

The step of making the nitrile may be Example I A plug composed of 55% by weight of microcrystalline wax having a melting point between 190 F. and 195 F. and 45% rosin amine stearate was found to effectively remove parafiin deposits from the interior of an oil flow line and dissolve in the oil within a period of several hours at a temperature of approximately 130 F.

Example I! A plug, which was found to be very effective in removing parafiin deposits from oil flow lines at temperatures in the'range of F. to F. and which was more soluble in the oil than the plug of Example I, was composed of 50% by.

weight of microcrystalline wax having a melting point of F., 25% asphalt with a melting point between 230 F. and 240 F. determined by ASTM ring and ball method and a penetration from 7 to 10, and 25% rosin amine stearate.

Example III Example IV Plugs composed of 50% of'the same asphalt as employed in Example II, 35% microcrystalline wax, and 15% rosin amine stearate were found to effectively remove parafiin deposits and dissolve at a satisfactory rate'in a surface oil line at temperatures between 80 F. and 100 F.

Plugs provided in accordance with this invention are satisfactory for removing parafiin deposits from any production tubing or other conduit through which oil flows. In the actual operation of scraping or cutting paraffin from the interior of such oil flow lines, the procedure is not one of using a plug of given percentages of base material such as wax or asphalt, or mixtures thereof, and a salt of rosin amine, but instead the percentages of such materials are varied to obtain, under the conditions of each case where it is desired to remove parafiin deposits, a plug having the aforementioned necessary characteristics, that is, sufficiently hard to provide an effective cutting surface, maintain shape and remain hard at temperatures in excess of those expected to be encountered in temporary storage places, sufiiciently soluble to dissolve in oil within a desired period of time, and will not shatter or break under the compression forces necessary to propel the plug through the conduit. This will be apparent when consideration is given to the fact that from location to location there are variations in the temperatures encountered in the oil flow lines, the composition'of the oil in which the soluble plug is required to dissolve, the time in which it is desired that the plug dissolve, theamount of parafiin deposited and other factors, which need not be mentioned. Field tests have indicated, for example, that the wax content may vary from 0% to 55 by weight, asphalt content from 0% to 90%, and rosin amine salt from 10% to 45%, dependent upon the particular conditions encountered.

It is to be noted that plugs may be provided preferably in accordance with this invention containing either asphalt alone, or wax alone as the base materials, or mixtures thereof. It is necesby weight of the rosin amine salt. The rosin amine salts are important to obtain the desired physical properties of the plug.

In the practice of the invention, a plug is formed by varying the percentages of the components until the necessary physical properties are obtained for the conditions under which the plug is to be employed. The plug is shaped to conform with the interior of the oil conduit and is adapted to fit snugly therein. The plug is then inserted in the conduit and oil under pressure is applied to one end thereof causing the plug to be propelled through the conduit, thereby removing paraffin deposits; While moving through the conduit and also after traveling to the end of the conduit with removal of all the paraffin deposited on the interior thereof, the plug will dissolve relatively slowly in the 011.

While a number of embodiments have been described above, it will be understood that this invention is susceptible of various other embodiments within the scope of the appended claims. For'example, the plugs may comprise solid, cylindrical shapes, or in the event that more rapid dissolution or disintegration is required, the plugs may be formed as hollow cylinders having one end closed so that the internal surface of the plug may be subjected to the solvent action of the oil in the conduit being cleaned. If

necessary, the hollow, cylindrical plugs may be formed with internal webs to give added strength, or the leading end of the plug, be it either solid or hollow, may be recessed or dished rather than flat.

We claim:

1. A plug for removing paraiifln from the wall of a conduit through which oil flows, including an oil-soluble base material and a rosin amine salt of an organic acid.

2. A plug for removing paraflin from the wall of a'conduit through which oil flows, including an oil-soluble base material and a rosin amine salt of a carboxylic acid having a molecular weight between 1'70 and 350.

3; A plug for removing paraffin from the wall of a conduit through which oil flows, including anoil-soluble base material and a rosin amine salt of a carboxylic acid selected from the group consisting of saturated fatty acids and naphthenic acids having a molecular weight between 170 and 350.

4. A plug for removing paraffin from the wall of a conduit through which oil flows, including asphalt and a rosin amine salt of an organic acid.

5. A plug for removing parafiin from the wall of a conduit through which oil flows, including an oil-soluble wax and a rosin amine salt of an organic acid.

6, A plug for removing paraiiin iron; the wall of a conduit through which oil flows, including an oil-soluble base material consisting of'asphalt and an oil-soluble wax, and a rosin amine salt of an organic acid.

7. A plug for removing paraflin from the wall of a conduit through which oil flows, including a high melting point asphalt'and a rosin amine salt of a carboxylic acid having .a molecular weight between 1'70 and 350.

8. A plug for removing paraflin from'the wall of a conduit through which oil flows, including a high melting point wax and a rosin amine salt of a.carboxlic acid having a molecular weight between 1'70 and 350.

9. A plug for removing paraffin from the wall of a conduit through which oil flows, including an oil-soluble base material consisting of a high melting point asphalt and a high melting point oil-soluble wax, and a rosin amine salt of a carboxlic acid having a molecular weight between and 350'.

10. A plug for removing parafiin from the wall of a conduit through which oil flows, including a high melting point asphalt, and a rosin amine salt of stearic acid.

11. A plug for removing paraffin from thewall' of a conduit through which oil flows, including a high melting point wax, and a rosin amine salt of stearic acid.

12. A plug for removing paraflin from the wall of a conduit through which oil fiows, including an oil-soluble base material consisting of a high melting point asphalt and a high melting point oil-soluble wax, and a roson amine salt of stearic acid.

13. A plug for removing paraffin from the wall of a conduit through which oil flows, including an oil soluble base material consisting of a high melting point asphalt and a high melting point oil-soluble wax, and a rosin amine salt of palmitic REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,343,136 Dobson Feb. 29, 194; 2,369,831 Jones Feb. 20, 1945 2,411,021 Landrum --.---..-r.-.--.-. Nov. 12, 1946 

1. A PLUG FOR REMOVING PARAFFIN FROM THE WALL OF A CONDUIT THROUGH WHICH OIL FLOWS, INCLUDING AN OIL-SOLUBLE BASE MATERIAL AND A ROSIN AMINE SALT OF A ORGANIC ACID. 